Patent GB-274583-A (GB)
Title: Improvements in projecting apparatus for moving picture machines
IPC: G03B41/08
Filed: 1926-04-28
Abstract: 274,583. Holman, A. J. April 28, 1926. Kinematograph apparatus. -in continuous-feed projectors having two rotating, overlapping, rings of refractory elements for optical compensation, the gate is adjustable along the optical axis for focusing, and the objective is adjustable along the optical axis, in accordance with the pitch of the film images, to secure exact registration on the screen of successive images; to reduce the occurrence of defects in the compensation, diaphragms of special shape may be used in conjunction with the objective, and opaque patches may be provided on the refracting elements. As shown in Fig. 7. the projector comprises a power driving shaft 8 geared by wheels 7, 5 to a hand driving shaft 4. The wheel 5 drives a wheel 88 on the shaft of the lower sprocket 89, and the sprocket shaft drives, through helical gearing 95, a vertical shaft 96 carrying a centrifugal governor 226 controlling a cut-off shutter, and driving an upper sprocket 105 through helical gearing 101. The wheel 5 also meshes with a wheel 17 on a countershaft 15 carrying a wheel 18 meshing with a wheel 19 on a cross-shaft 20. The shaft 20, Fig. 5, carries oppositely cut worms 31, 37, driving worm wheels 32, 38 on the shafts 42, 43 of the rings of refractory elements, and is movable axially by adjustable bushings 35, 36 so that the relative rotative positions of the rings of refractory elements may be varied The refracting elements 56, Fig. 4, comprise plano-convex lenses cut so as to have straight, contiguous, edges which are radial to the centre of each ring shaft 42, 43; means for clamping them to spiders on the shafts 42, 43, comprising paper pads for heat insulation &c., are described. The objective 77 is carried by a mount 66, adjustable axially by a rack 64 and pinion 73; and the mount also carries diaphragms 79, 84, the diaphragm 79 being provided with an aperture 78 having upper and lower V-shaped projections 80, 81, Fig. 15, and the diaphragm 84 being provided with an aperture having sides corresponding in curvature and alignment with the outer peripheries of the rings of elements 56, and having a vertical height which diminishes from the sides to the middle of the aperture. Patches 61. Fig. 15, of black linen tape &c. may be placed on the elements 56. across their radial edges, and serve with the aperture 78 to limit the effective areas of the elements, and reduce the image movement on the screen. The sum of the angle subtended by each element at the centre of the ring shafts 42, 43, and the angles B between the line joining the centres of the shafts 42. 43 and the lines from the centres to the top of the aperture 78, may be substantially 29‹, so as to limit the image movement to about a quarter of an inch for a screen image having a height of about twelve feet. The gate comprises a member 117, carrying an aperture plate 123, Fig. 12, having curved film tracks 124 and an aperture height of two and three quarter times a picture, the member 117 being carried by rods slidable in bosses 113, 114, Fig. 5. and being adjustable for focusing by a knob 122, Fig. 7, on a spindle 120 carrying a pinion engaging a rack 118 carried by the member 117. A gate frame 197, movable axially with respect to the member 117 to open the gate, is carried by rods 191, 192 slidable within the rods carrying the members 117, and by a plunger 186, normally pressed by an encircling spring to close the gate. Linkwork is described by which the gate may be opened, and held open, by the operation of a hand-lever 193, Fig. 4, on a shaft 175. The frame 197 carries a presser frame 212 acted upon by two bow springs 216. The member 117 carries a lower sprocket 141, driven by gears 142, 148, 149, 153, 154, Fig. 4, from the shaft 20, and an upper roller 128. The roller 128 has a flange 129, Fig. 9, on a part secured to a shaft 127, and a flange 130 on a part 131 axially movable on the shaft and pressed by a spring 133. The shaft 127 is movable axially, and transversely of the optical axis, by adjustment of a screwed bearing bush 135. The frame 197 carries a curved plate 207. Fig. 12, embracing the sprocket 141, and fitted with spring-pressed fingers 208 bearing on the film margins; it also carries a pressure roller 204 engaging the roller 128 under the action of a spring 205 on a pivoted bracket 203. Pressure rollers 90, 106. Fig. 4, are also provided for the sprockets 89. 105 respectively, each roller being carried by a bracket 107 pivoted on a screw 108 and held in or out of operative position by a pin 109 in engagement with a spring 110; a setscrew 111 enables the pressure to be adjusted. The cut-off shutter 233, Fig. 4, is slidable vertically on rods 236, and is operated by an arm 232 linked to a pivoted arm carrying a roller riding on a flange 221, Fig. 7, of the governor. The governor comprises an annular weight 226 divided into halves, each carried by a link 225, and connected by links 227 to a sleeve 220 carrying the flange 221. The construction of the casing of the apparatus is described in detail in the Specification, and comprises a web 2, housings for the worm wheels 32, 38, &c., a box 243 supporting the upper spool box and containing rollers 245, and doors at the sides, one of the doors being provided with a glass window. Specification 274,793 is referred to.